Elixir of Portobello

Mix first 4 ingredients (the dry ingredients) in a large bowl. Make a well in dry ingredients and add 1/2 cup vegetable oil then the 5 unbeaten egg yolks, then the orange juice and orange rind. Beat with a spoon until smooth. In another large mixing bowl, whip the 1 cup egg whites and 1/2 teaspoon cream of tartar until very stiff. Pour the egg yolk mixture gradually over whipped egg whites. Gently fold into egg whites; DO NOT STIR. Pour into ungreased 10 inch x 4 inch deep tube pan. Bake in preheated 325 degree oven for 65-70 minutes. Upon removing cake from oven, immediately turn pan upside down, placing tube part over the neck of a funnel or bottle if your pan does not have legs. Let hang free until cold. Loosen from sides with a spatula and turn out onto serving plate. Spread with Orange Butter Cooked Icing. Orange Butter Cooked Icing Melt 1/2 cup butter or shortening (should be at least 1/2 butter for flavor) in a large saucepan and blend in 4 Tablespoons cake flour and 1/4 teaspoon salt. Slowly stir in 1/2 cup orange juice. Bring to a boil and boil 1 minute. Mixture may appear curdled, but do not despair. Remove from heat and stir in 3 cups powdered sugar. Beat until of spreading consistency. (If this is taking a long time, set saucepan into a larger pan of cold water. Stir in 1 Tablespoon grated orange rind. Spread on cooled cake. Variation: Use frozen strawberries that you have pureed in a blender instead of orange juice and rind. (Great for Valentine's Day or Sweet Sixteen parties.)